1 TITLE PAGE Prevalence of pregnancy after breast cancer, reproductive outcomes and maternal safety: a systematic review and meta-analysis Matteo Lambertini 1,2* , Eva Blondeaux 1,3* , Marco Bruzzone 4 , Marta Perachino 1,2 , Richard A. Anderson 5 , Evandro de Azambuja 6 , Philip D. Poorvu 7 , Hee Jeong Kim 8 , Cynthia Villarreal-Garza 9, 10 , Barbara Pistilli 11 , Ines Vaz-Luis 11 , Cristina Saura 12 , Kathryn J. Ruddy 13 , Maria Alice Franzoi 6 , Chiara Sertoli 1 , Marcello Ceppi 4 , Hatem A. Azim Jr. 9 , Frédéric Amant 14,15 , Isabelle Demeestere 16 , Lucia Del Mastro 1,3 , Ann H. Partridge 7 , Olivia Pagani 17 , Fedro A. Peccatori 18 *contributed equally Author Affiliations 1 Department of Internal Medicine and Medical Sciences (DiMI), School of Medicine, University of Genova, Genova, Italy 2 Department of Medical Oncology, U.O. Clinica di Oncologia Medica, IRCCS Ospedale Policlinico San Martino, Genova, Italy 3 Breast Unit, IRCCS Ospedale Policlinico San Martino, Genova, Italy 4 Clinical Epidemiology Unit, IRCCS Ospedale Policlinico San Martino, Genoa, Italy 5 MRC Centre for Reproductive Health, The Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK 6 Department of Medicine, Institut Jules Bordet, Université Libre de Bruxelles (U.L.B.), Brussels, Belgium 7 Department of Medical Oncology, Dana-Farber Cancer Institute, Boston MA, USA. 8 Department of Surgical Oncology, Asan Medical Center, Seoul, Korea